Integrated Pest Management of Redberry Mite, Acalitus essigi, on blackberries - Dr Stephen Quarrell Research Fellow in Entomology
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Integrated Pest Management of
Redberry Mite, Acalitus essigi, on
blackberries
Dr Stephen Quarrell
Research Fellow in Entomology
Overview
• Redberry mite and disease
• The project…
• IPM overview and results so far
• Cultural
• Biological
• Chemical
• Sampling
Redberry mite
• Acalitus essigi
• Colour: whitish
• Size: 0.5 mm long
• Shape: wormlike, with legs at one
end of the body long
• Little is known about their lifecycle
100µm
RBM lifecycle 2. In spring, the mites
move onto the developing
shoots. The cane growth
moves them through the
1. Overwinter in bud canopy
scales or deep in buds.
3. Then under
bracts on stems and
beneath flowers
5. During ripening, move
into the developing 4. As flower buds appear,
drupelets, generally under the mites work their way
the calyx and around the into the buds
core
Redberry Disease • Drupelets, remain green or red and hard whilst the remaining drupelets ripen normally • Often around the calyx • Enzymes in the mite’s saliva stopping ripening • Disease levels increasing in some areas and with some varieties
Fruit Quality - Delayed Ripening • Observed in both Tas and Vic. • Red drupelets soft • Signs red drupelets will ripen • Drupelets at tip over- ripe → not marketable • No RBM found • Environmental???
Fruit Quality - Poor Pollination
Uni Of California Extension: https://ucanr.edu/blogs/blogcore/postdetail.cfm?postnum=7561
Tasmanian Victoria – Feb 2020
Cultural Control
• Practices that discourage pest
invasion or make the crop less
suitable
• Prevention is better than cure!
Examples
• Varieties
• Pruning/canopy
management
• Farm Hygiene
• Weed management
• Plant nutrition
Variety v’s RBM
18
16
14
12
Average RBM per fruit
10
8
6
4
2
0
BL454 Chester Cowles Elvira Apache Karaka Loch Ness Ouachita Thornfree Victoria
Variety
Cultural - varieties
• Further complicating variety
differences is canopy management
• Floricane versus primocane
• Mow down pruning reduces over
wintering populations
• Remember: Elvira → no RBM
From Murrietta and Gaskell (2016)Hygiene & Wild Blackberries
• All growers reported the removal and
burning of pruned canes
• 75 % of growers reported having
blackberries on or near their farms
80 y = -0.7613x + 49.19
R² = 0.5022
• Crops with wild blackberries > 80 m away 70
Redberry disease incidence (%)
60
appear to show no signs of damage 50
40
• Reducing wild blackberries on-farm 30
20
maybe an easy way to reduce pest 10
pressure! 0
0 20 40 60 80
Distance from wild blackberries (m)Biological control
• You are probably currently using:
• Californicus and Persimilis for two-
spotted mite
• Neoseiulus cucumeris for broad mite
and western flower thrip
• No known predator for RBM
• 2018/19 season
• Occi and Lailae
• 2019/20 season
• Lailae and DoreenBiological control of RBM
• There are currently no known biological
controls for RBM
• Commercially available species assessed:
• Thyphlodromus occidentalis (2018/19)
• Typhlodromalus lailae (2018/19 & 2019/20)
• Thyphlodromus doreenae (2019/20)
• Druciarek et al. (2018) propose that
californicus may help control RBM???Beneficial species in blackberry buds and fruit
0.9
Fruit buds
0.8
Average number of predatory mites
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
VarietyRatio of RBM to Predators
• Recommended ratio for broad mite control > 0.1 (Johnson and Garcia 2015)
• No ratio for RBM
30 0.005
26.50
0.004
25
0.004
20
0.003
0.003
15
0.002
10
7.00
0.001
5
0.01 0.02 0.00 0.00
0 0
Wild BL454 Chester Karaka Ouachita Thornfree Wild BL454
http://www.smallfruits.org/assets/documents/reaserch/2015/2015-06.pdf0.9 RBM
Biological control of RBM cont… 0.8
0.7
Mean RBM fruit-1 (±SEM)
0.6
• Neither occi or lailae seen on fruit so 0.5
far 0.4
0.3
• Lailae and occi rows also had higher 0.2
0.1
RBM 0
Green Red Ripe (early) Ripe (late)
• But ‘Doreen’ looks promising! 0.4
Fruiting stage
• Ratio nearly 1:1 (0.194 : 0.136) 0.35
T. doreenae
Predators
Ty. lailae
0.3
Mean Phytoseiid mites fruit-1
Control (unsprayed)
• Another species (T. dossei) being 0.25
isolated from Victorian fruit 0.2
• Tasmanian samples yet to be
0.15
identified 0.1
0.05
0
Green Red Ripe (early) Ripe (late)
Fruiting stageChemical management strategies
• Applications of pesticides that are highly toxic to predators have the
most devastating effect on biological control of mites.
• Can take several months for predator populations to build up again
after the pesticide application
• So any pesticide applications should be consider and potential
negative effects
• Two windows have been highlighted for successful RBM control:
• End of winter
• From bud formation to first floweringChemical
management cont…
• All but 1 grower used a fungicide program
throughout the growing season, primarily
aimed at Botrytis.
• The most frequently used fungicides
included:
• mancozeb
• captan
• pyrimethanil (Scala)
• boscalid + pyraclostrobin (Pristine)
• chlorothalonil (Bravo)
• fenhexamid (Teldor)
• azoxystrobin (Amistar)
• cyprodinil (Switch)Fungicide toxicity and RBM
• Although there are obvious insect issues in
blackberry, fungal control may the key to
reducing RBM
• Mancozeb known to be highly toxic to
predatory mites (Bernard et al. 2004)
• Sulphur (Kumulus) known to be less toxic
(Thompson 2012)
• Impacts vary between species and
products
• Cucumerus susceptible to OPs
• Occidentalis tolerates OPs and resistant to
azinphos-methyl
Bernard et al. (2004) https://doi.org/10.1093/jee/97.3.891
Thompson (2012) http://www.mvwi.com.au/items/511/2012-05-FS-Pesticide-Impacts2.pdfNZ Boysenberry Program • The application of sulphur (Kumulus) or lime sulphur 2 to 3 times from early September to the end of October. • Kumulus IMF (800 g/kg S) is applied at varying rates and water rates with the most common being 450 g/100 L in 600 l/Ha of water. • Lime Sulphur (200 g/L S) applied at 5 L/Ha in a water rate of 600 to 650 L/Ha.
RBM chemical control –
other recommendations
• Cross et al. (2012) (East Malling) - recommended
2 abamectin applications at 5% flower and again
2 weeks later
• Achieved good mite control with abamectin
but still observed damage - other causes???
• Didn’t assess the impact of earlier
applications
• Colleagues went on to examine whether viruses
could be responsible
• Found several viruses but none are mite
transmittedOther chemical recommendations cont…
• UC IPM Extension: lime sulphur application depends upon variety and
RBM severity.
• For blackberry varieties that retain a leaf through winter, begin lime sulphur
applications at bud break and continue at 3-week intervals up to 12 days
before harvest.
• For blackberry varieties that naturally defoliate over the winter, apply lime
sulphur at bud swell (80 lt/1000) and again at first bloom (25 lt/1000)
• Lime sulphur: more toxic to apple rust mite than to Occidentalis
• No permit for Lime Sulphur on Rubus in Aust. Wettable S?0.9 T. doreenae Ty. lailae
Spray reduction Trial 2019/20 0.8
0.7
Control (unsprayed) Control (sprayed)
Mean RBM fruit-1 (±SEM)
0.6
• Conducted at Costa’s (Bengeo Rd) 0.5
0.4
• Full program versus no mancozeb or 0.3
Abamectin at 10 % bloom 0.2
0.1
• Predatory mites released in rows with mod. 0
Green Red Ripe (early) Ripe (late)
program 0.4
0.35
Results
Mean Phytoseiid mites fruit-1
0.3
• Best control with full program
0.25
• Lowest RBM
• But predator numbers heavily impacted 0.2
• Doreen 2nd 0.15
0.1
No difference in damage between treatments!!! 0.05
0
Green Red Ripe (early) Ripe (late)
Fruiting stageMite extraction
New extraction method
‘Shake and wash’ method
• 20 fruit per block recommended with calyx
• We do 40 to make sure
• Vial containing 2 ml of either:
• 70% ethanol
• methylated spirits (metho) Individual dried fruit in a cap vial containing 2ml
• dilute bleach & water ethanol
• detergent & water
• Shake for 1 minute.
• Liquid poured on a petri dish with black car underneath
for better visual contrast
• Count and/or ID the mites (20x magnification dissecting
microscope).
Petri dish with a gridded black
Perspex card underneathBud sampling
Why?
• RBM mite dispersed throughout the canopy
• Performed out of season (predictive)
• Enables early development of management
strategies
• Buds dissected and then washed/agitated in
ethanol or…. as per fruit
• Minimum of 7 buds per block recommended
• We do 20 to make sureFruit versus Bud sampling
35
• Far greater chance of detecting 30
Fruit
RBM in buds Buds
Av. RBM per plant part
25
• Probability of 50% detection of 20
RBM, winter bud sample size
needed is 7 15
10
• Probability of 50% and 80%
detection for predatory mite are 5
15 and 57 winter buds 0
respectively
VarietyWhat mite is that?
Eriophyid mites Phtyoseiid mites
• Pests (RBM…) • Predatory
• Long, worm-like • Rounded body
• Legs at one end • Enlarged mouth partsWhat mite is that?
Tetranychid mites
Tarsonemid mites Tydeid mites • TSM…
• Broad mites • Predators, fungivores… • Larger, spherical
• Round, hairy • Oval shaped • Large stylets (mouth parts)
• Small mouth parts • Web spinningYou can also read
